Robert S. Barnes

The truth of a fact can only be proved by a fact, not by reasons or reasoning. Reasons and reasoning can establish its probability or its
necessity but can never prove its actuality. The veracity of a
messenger can only be proved by his sender, the sending of Moses only
by God himself. That is why no word of an answer from Moses himself
could refute the accusation of Korach. If God would not consider it
right to confirm the veracity of his being commissioned by God, in
face of this denial of it, then his mission was at its end -- ויפל על
פניו.